This application claims the priority of 198 43 760.9, filed Sep. 24, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a device for reforming, in particular for embossing, the edge of ring-shaped or disc-shaped blanks.
Particularly in coin production, but also in other instances of use, it may be necessary to deform a flat disc-shaped blank at its edge. If, for example in the production of medals or coins, round or polygonal disc-shaped blanks have first been stamped out of a sheet of suitable material (e.g., metal), they have, at their edge, a stamping burr and a parting plane which originates from the stamping operation. In many cases, blanks of this kind cannot be embossed immediately on the flat side.
In particular, embossing cannot occur when the nature of the outer edge of the blank has to meet special quality requirements, as is often the case with coins. Moreover, there is occasionally the need to be able to design the edge in a specific way. For example, coins often have a thickened or raised edge which forms an annular rib projecting above the flat sides of the coin. The formation of such a rib makes it necessary to carry out, on the edge, an upsetting operation in which material is pressed inwards in the radial direction.
Furthermore, coins with knurling or edge lettering or any other raised or recessed edge structure are in use. Edge lettering can likewise be produced only by machining the coin in the radial direction. Coins, in which, for example, raised lettering is made in a recessed groove on the edge of the coin, are particularly demanding. Coins of this kind are shaped on the edge of the round blank. The length of the abutment element is at least such that the abutment element and the roll-forming segment completely reform the circumference of the round blank. If no edge lettering or no other raised formed elements are to be produced on the round blank, the circumference of the round blank may be rolled more than once.
If the lengths of the abutment element and of the roll-forming segment are coordinated so that the complete circumference of the round blank touches the reforming elements exactly once, raised formed elements may also be produced on the round blank. Consequently, part of the circumference of the round blank is formed or determined by the roll-forming segment of the forming wheel and another part of the round blank is formed or determined by the abutment element. This avoids one and the same edge region of a coin or round blank being rolled more than once.